1. Field of the Invention
The present invention relates to an image recording apparatus for recording an image on a printing plate, and particularly to an image exposure apparatus having an apparatus for performing the positioning in a state that the printing plate is put on a plate feed guide.
2. Description of the Related Art
The conventional image exposure apparatus is to record (expose) an image on a printing plate consisting of an aluminum foil sheet. In the image exposure apparatus, a plate feed conveying section is provided with a reversing unit and a conveyer. The reversing unit transmits to the conveyer a printing plate drawn out from a cassette through rolling up on a reversing roller. The conveyer conveys obliquely below the printing plate put on a conveying belt while supporting the printing plate in cooperation with the roller so that the top of the printing plate is in contact with a pin roller. When the printing plate is in contact with the pin roller, the plate feed conveying section causes a positioning motor to operate so that the reversing unit moves together with the conveyer on a parallel basis. Thus, the printing plate is in contact with the pin roller to perform the positioning of the printing plate. The printing plate subjected to the positioning is fed to a puncher by the conveyer in the leading edge (cf. for example, Japanese Patent Application Laid Open Gazette TokuKai. 2001-356489 (Page 1, FIG. 2).
According to the image exposure apparatus as mentioned above, the printing plate, which is put on a plate feed guide formed as a plate, is conveyed to a punch section to form punched holes on the printing plate through performing a punch processing. The punched holes are used for a determination of positioning in a printing processing, which is the continuation step. The printing plate, which is put on the plate feed guide, is conveyed to an exposure section and is wound on a rotating drum of the exposure section. Then the printing plate is subjected to an exposure processing.
By the way, there is a necessity for making sure of reproduction quality of exposure recording positions, in which the exposure recording positions on a plurality of printing plates are given with uniformity in its entirety. For this reason, before the exposure processing by the exposure section, there is performed the following positioning in a state that the printing plate is put on the plate feed guide.
As shown in a part (a) of FIG. 10, a printing plate 12 is put on a plate feed guide 20, a front edge of the printing plate 12 is in contact with a pair of positioning pins 48 located in the vicinity of a punch section (not illustrated), and a width direction moving unit 39 provided on the plate feed guide 20 advances in the direction of the printing plate 12. At a moving member 114 of the width direction moving unit 39, a connecting lever 115 is rotatably mounted on a fulcrum 116. At the connecting lever 115, a conveying pin 42 is rotatably supported on a supporting shaft 40. A pressurizing spring 119 enables the connecting lever 115 anticlockwise (the arrow direction in FIG. 10), that is, in a direction that the conveying pin 42 moves forward.
As shown in a part (b) of FIG. 10, when the width direction moving unit 39 moves forward, the conveying pin 42 is elastically in contact with a width direction edge of the printing plate 12 to move in the right direction, so that the right edge of the printing plate 12 is in contact with a reference pin 36 and thereby carrying out a positioning in the horizontal direction.
Recently, in an image exposure apparatus for recording an image on a printing plate, there is a tendency that sorts of size and thickness of the printing plate, with which one image exposure apparatus is capable of coping, are increased. For example, there are used printing plates of 0.15 mm, 0.2 mm, 0.24 mm, 0.3 mm, and 0.4 mm in thickness, and width 300 mmxc3x97length 458 mm in smallest one and width 1310 mmxc3x97length 1050 mm in largest one with respect to the size. Of course, the smaller in thickness or the larger in size, the buckling deformation strength more weakens.
Hitherto, the pressure applied to the printing plate 12 via the conveying pin 42 is determined by the pressurizing spring 119 and is constant pressure. Accordingly, hitherto, the pressurizing spring 119 is set up in such an extent that the printing plate 12 is subjected to the buckling deformation and is pressed against the reference pin 36. This scheme is available in the event that the sort of the printing plate is not many. But the smaller in thickness or the larger in size and the larger in width make it difficult to be matched with only the spring force of the pressurizing spring 119. More specifically, too weak spring force of the pressurizing spring 119 brings about lack of pressing, and too strong spring force of the pressurizing spring 119 brings about buckling deformation. As a result, there is raised a poor positioning.
In view of the foregoing, it is an object of the present invention to provide an image exposure apparatus capable of setting up the optimum pressurizing at the conveying pin in accordance with the thickness or the width size of the printing plate and thereby preventing the buckling deformation and the poor positioning of the printing plate.
To achieve the above-mentioned object, the present invention provides an image exposure apparatus comprising:
a plate feed guide that conveys a printing plate for recording an image by an exposure head to a rotating drum for winding and a punch unit for forming punched holes to be used for positioning, the punch unit being provided upper the rotating drum;
a width direction moving unit that moves a conveying pin in a width direction of the printing plate while the conveying pin is in contact with a width direction edge of the printing plate, the width direction moving unit being put on the plate feed guide; and
a reference pin disposed at an opposite side of the width direction moving unit for defining the width direction edge of the printing plate,
wherein the width direction moving unit comprises:
a moving member moved by a driving motor in the width direction of the printing plate;
pressurizing means for enabling the conveying pin supported by the moving member in a direction of the printing plate;
a plurality of pin position detecting sensors that detects a moving position of the conveying pin wherein the moving member moves forward in the direction of the printing plate and the conveying pin is moved by coming into contact with the width direction edge of the printing plate; and
control means having input means for entering a sort of the printing plate, the control means stopping the driving motor in accordance with a detection signal generated from the pin position detection sensor associated with the sort of the printing plate entered through the input means of the plurality of pin position detecting sensors.
According to the image exposure apparatus of the present invention as mentioned above, the positioning of the printing plate in the width direction is carried out in such a manner that in the state that the printing plate is put on the plate feed guide, the conveying pin is moved in the width direction of the printing plate to press the edge of the printing plate so that the printing plate bumps the reference pin.
At that time, the conveying pin is pushed by the edge of the printing plate and moves. When the first pin position detecting sensor detects the movement of the conveying pin, the driving motor stops by a signal of the control means based on the detection signal of the first pin position detecting sensor. Likely, when the second pin position detecting sensor detects the movement of the conveying pin, the driving motor stops by a signal of the control means based on the detection signal of the second pin-position detecting sensor. The detecting position of the first pin position detecting sensor is a detecting position involved in a case where the printing plate is of the thinnest or is large in width. The detecting position of the second pin position detecting sensor is a detecting position involved in a case where the printing plate is of the thickest or is small in width. Thus, according to the present invention, it is possible to apply the optimum pressurizing force of the conveying pin to the printing plate in accordance with the strength of the printing plate, and also to convey the printing plate with the optimum pressurizing force while preventing the buckling deformation of the printing plate.
In the image exposure apparatus according to the present invention as mentioned above, it is preferable that the pressurizing means comprises a connecting lever rotatably supported on the moving member, wherein the conveying pin is mounted on the connecting lever, and a pressurizing spring coupled with the connecting lever for enabling the conveying pin in the direction of the printing plate.
In the image exposure apparatus according to the present invention as mentioned above, it is preferable that the conveying pin is rotatably supported by the connecting lever.
In the image exposure apparatus according to the present invention as mentioned above, it is preferable that the pin position detecting sensors detect a connecting position of the connecting lever.
In the image exposure apparatus according to the present invention as mentioned above, it is preferable that the pin position detecting sensors detect the width direction edge of the printing plate.
In the image exposure apparatus according to the present invention as mentioned above, it is preferable that the width direction moving unit has an edge detecting sensor for detecting the width direction edge of the printing plate first when the moving member moves forward in the direction of the printing plate, the driving motor is changed over to a lower speed in accordance with an instruction of the control means based on a detection signal of the edge detecting sensor.